1. Field of the Invention
The present invention relates to a honeycomb structure.
2. Discussion of the Background
In recent years, particulate matters (hereinafter, also referred to simply as PMs) in exhaust gases that are discharged from internal combustion engines for vehicles and construction machines and the like have raised problems as contaminants harmful to the environment and the human body.
In order to solve those problems, as an exhaust gas purifying device for purifying exhaust gas by capturing PMs in exhaust gas, there have been proposed, for example, various exhaust gas purifying apparatus using a honeycomb structure as a structural element.
The honeycomb structure of this kind is made of, for example, porous ceramic such as silicon carbide, and includes a large number of cells which are placed in parallel with one another with a cell wall interposed therebetween, inside thereof from one end to the other end along the longitudinal direction of the honeycomb structure. Further, one of the ends of each of the cells is sealed with a plug material.
With this structure, exhaust gas flows into cells that open on the exhaust gas inlet side and passes through a cell wall separating adjacent cells and then flows out through cells that open on the exhaust gas outlet side. As a result, PMs in the exhaust gas are captured in the cell wall.
At a timing when a predetermined amount of PMs has accumulated and the pressure loss reaches a certain value, the honeycomb structure is heated for regenerating process. As a result, the accumulated PMs are burned so that the PM capturing ability of the honeycomb structure is recovered.
With regard to the honeycomb structure of this kind, there has been a demand in these days for a large size honeycomb structure capable of capturing a large amount of PMs to be mounted in large scale diesel engines for heavy vehicles such as buses and trucks, agricultural machinery, construction machinery, ships and vessels, locomotives, and the like.
An example of the honeycomb structure designed for large scale models includes a honeycomb structure formed of a ceramic block in which a plurality of honeycomb fired bodies made of porous ceramics such as silicon carbide are combined with an adhesive layer interposed therebetween, and a sealing material layer formed on the periphery face of the ceramic block (for example, JP-A-2008-179526).
The contents of JP-A-2008-179526 are incorporated herein by reference in their entirety.